Dirhinus quadrhinus Delvare & Copeland 2018

Key to species of the quadrhinus species group of Dirhinus

1 Body with extremely long setae on labrum, mandibles, gena posteriorly, pronotal collar laterally, propodeum laterally, adscrobal area of mesepisternum, metepimeron dorsally, procoxa (Fig. 120), metacoxa, and pro- and metafemora on outer side (Fig. 124). In dorsal view, distance separating median ocellus from end of scrobal depression about as large as ocellus diameter (Fig. 121).................................................................. D. gigasetosus Delvare sp. nov.

- Body without such outstanding setation, the setae always shorter (Figs 112, 141, 148). Distance separating ocellus from end of scrobal depression much greater than ocellus diameter (Figs 114, 133, 142, 150).................................... 2

2(1) Frons without preorbital ridge (Figs 149, 151). Dorsal surface of petiole less transverse than in alternate, about 1.5× as wide as long. Pedicel relatively short, 1.67× as long as wide. In dorsal view, inner edges of inner pair of horns diverging at an angle of about 30° (Fig. 150), and apex of inner horn extending beyond that of outer horn.......... D. leakeyorum Delvare sp. nov.

- Frons with preorbital ridge (Fig. 115). Dorsal surface of petiole more transverse than in alternate, 2.15–2.25× as wide as long (Figs 118, 138, 146). Pedicel at least 2× as long as wide (Figs 116, 134). In dorsal view, inner edges of inner pair of horns diverging at a more acute angle (about 20°) (Fig. 114), or apex of inner horn not exceeding that of outer horn............. 3

3(2) Median ocellus more distant from end of scrobal depression than in alternate, e.g. in dorsal view inner horn length (IHL, Fig. 6) 1.44× as long as distance from median ocellus to end of scrobal depression (Fig. 114). Inner edges of inner pair of horns diverging at an angle of about 20°. Apex of inner horn extending past that of outer horn. Submedian carinae on dorsal surface of petiole diverging posteriorly.................................................. D. quadrhinus Delvare sp. nov.

- Median ocellus less distant from end of scrobal depression, e.g. in dorsal view IHL 1.65–2.29× as long as distance from median ocellus to end of scrobal depression (Figs 133, 142). Inner edges of inner pair of horns diverging at an angle of about 30°. Apex of inner horn not exceeding that of outer horn. Submedian carinae on dorsal surface of petiole, when visible, slightly converging posteriorly................................................................................. 4

4(3) Dorsal surface of petiole strongly sloping backwards (Fig. 139) and with distinct submedian carinae delimiting a median sulcus (Fig. 138). Strigose surface on first gastral tergite mostly smooth between the longitudinal ridges (Fig. 140). IHL 1.65× as long as distance from anterior edge of median ocellus to end of scrobal depression (Fig. 133)... D. kambae Delvare sp. nov.

- Dorsal surface of petiole hardly sloping and with vestigial submedian carinae, hence median grove absent (Fig. 146). Strigose surface on first gastral tergite reticulate between longitudinal ridges anterolaterally (Fig. 147). IHL 2.29 × as long as distance from anterior edge of median ocellus to end of scrobal depression (Fig. 142)................ D. maasaii Delvare sp. nov.